The Kaplan-Meier Estimator is a statistical tool used to estimate the survival function from lifetime data. It helps researchers understand the time until an event occurs, such as death or failure, by providing a visual representation of survival rates over time. This method is particularly useful in medical research and reliability engineering. The estimator calculates the probability of survival at different time points, taking into account censored data, which refers to instances where the event has not occurred by the end of the study. The resulting survival curve allows for comparisons between different groups, enhancing the understanding of factors affecting survival.